Effects of zinc supplementation during pregnancy on pregnancy outcome in women with history of preterm delivery: A double-blind randomized, placebo-controlled trial

Methods. A double-blind placebo-controlled randomized clinical trial was conducted between January 2007 and June 2008. Eighty-four pregnant women with a previous preterm delivery age 19 to 35 years were randomly allocated to receive either 50 mg/day Zn as Zn sulfate or placebo from 12 to 16 weeks of gestation till delivery. Pregnancy outcome was assessed in term of incidence of intrauterine growth retardation (IUGR), birth weight, crown-heel length, head circumference, Apgar score, and gestational age at delivery. Results. The mean birth head circumference was higher in Zn supplemented group than in the placebo group (35.0 cm vs. 33.7 cm, P < 0.05). Although gestational age at delivery (37.1 week vs. 36.7 week) and birth weight (2960.6 g vs. 2819.0 g) of babies born in Zn supplemented group was slightly higher than placebo group, it was not statistically significant. No significant differences were seen for infant length, Apgar score, and IUGR. Conclusions. Adding Zn supplementation during pregnancy to routine care of women with a previous preterm delivery had no significant effect on the gestational age at delivery and birth weight but increased the birth head circumference.